1. Field of the Invention
This invention relates to a method of fabricating a liquid crystal display, and more particularly to a method of fabricating a ferroelectric liquid crystal display that is capable of preventing inadequate injection of a liquid crystal.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) includes a plurality of liquid crystal cells arranged in a matrix. Each liquid crystal cell changes a liquid crystal alignment state in accordance with an applied electric field to control the transmittance of light, thereby providing a gray scale.
A ferroelectric liquid crystal, among other liquid crystals utilized in liquid crystal displays, has the fastest response speed on the order of many microseconds (μs) to a few milliseconds (ms), because ferroelectric liquid crystal material can polarize in the absence of an applied electric field. In addition, ferroelectric liquid crystal material can provide a wide viewing angle, for use in-Plane Switching (IPS), without any special electrode structure or alignment film. Accordingly, the ferroelectric liquid crystal is capable of producing a motion picture display represented in a liquid crystal TV.
Generally, as temperature of the ferroelectric liquid crystal decreases, the liquid crystal exhibits a phase-transition process as follows:
Isotropic Phase→Chiral nematic (N*) phase→Smectic C* (Sm C*) Phase→Crystal.
In such a phase-transition process, a ferroelectric liquid crystal display utilizes the smectic phase, which is a ferroelectric liquid crystal phase that exists at a normal (i.e. room) temperature.
The ferroelectric liquid crystal in the smectic phase is provided by injecting and cooling the liquid crystal, which exhibits the isotropic phase or nematic phase. A problem related to inadequate injection occurs because the volume of the liquid crystal decreases upon its phase-transition to the smectic phase.
FIG. 1 is a figure briefly illustrating a liquid crystal injection device for injecting the liquid crystal into a liquid crystal panel.
The liquid crystal injection device in FIG. 1 includes a chamber 12 and a liquid crystal tray 16 which is located within the chamber and connected with an injection hole 14 of a liquid crystal panel 10. Also, the liquid crystal injection device outside of the chamber 12 further includes a heater (not shown) for heating and controlling the temperature of the liquid crystal panel 10 and the liquid crystal tray 16, and a pressure controller (not shown) controlling the inner pressure of the chamber 12. The transition process of the liquid crystal to the desired ferroelectric liquid crystal phase using the aforementioned liquid crystal injection device is as follows.
Firstly, in an exhaust process using the pressure controller, a vacuum state, that is, a state of an equal pressure, is created inside of the chamber 12 and the liquid crystal panel 10. Afterwards, the injection hole 14 of the liquid crystal panel then contacts the liquid crystal tray 16. At the same time, because the liquid crystal panel 10 and the chamber 12 remain in the vacuum state, the liquid crystal in the liquid crystal tray 16 is not injected into the liquid crystal panel 10. Subsequently, N2 gas is injected into the chamber 12 using the pressure controller to make the inner pressure of the chamber 12 higher than the inner pressure of the liquid crystal panel 10. Due to such an inner pressure difference between the chamber 12 and the liquid crystal panel 10, the liquid crystal in the liquid crystal tray 16 is injected into the liquid crystal panel 10 through the injection hole 14. The difference in inner pressure between the chamber 12 and the liquid crystal panel 10 is increased, thereby easily injecting the liquid crystal into the liquid crystal panel 10. At the same time, the liquid crystal panel 10 and the liquid crystal tray 16 both sustain a high temperature, that is, sustain a liquid crystal injection temperature.
Next, the liquid crystal injected into the liquid crystal panel 10 and the liquid crystal panel 10 are cooled down under a certain pressure to make the liquid crystal undergo a phase transition from the isotropic phase or nematic phase to the smectic phase, which is a ferroelectric liquid crystal phase. Accordingly, the liquid crystal injected into the liquid crystal panel 10 experiences a volume decrease of around 3% upon its phase-transition to the smectic phase. As a result of this volumetric decrease, a problem related to inadequate injection of the liquid crystal occurs and a band configured perpendicular to the direction of the liquid crystal injection is formed where liquid crystal material is not injected.